Rufang Li

On the Sum of the Second Zagreb Index and Its Reciprocal Index for Tricyclic Graphs

For a simple connected graph G, let dG(u) denote the degree of a vertex u. The second Zagreb index Z2(G)=∑uv∈E(G)dG(u)dG(v) and its reciprocal index mZ2(G)=∑uv∈E(G)1/(dG(u)dG(v)) are widely studied topological indices in graph theory. Their sum Z2(G)+Z2m(G) has been studied for t...